I wanted to make a default replacement of a Maxis mesh, but when I exported and then imported it into Blender, I noticed that the faces are randomly separated.
Is there any solution to get the mesh import correctly? I'm not good enough with Blender to understand what the issue is.

Here are some pics, how it looks in SimPE and in Blender

It's a common issue with Blender. It doesn't translate smoothing from other programs or game meshes properly, so if you want this to stick, you need to fix it with the "Remove Doubles" function (it removes the extra vertices in edge splits, combining them into a whole mesh. It usually preserves the UVmap, but it can be an idea to do this step last if you're making large changes).

Don't do it everywhere, though - it smooths the mesh, but can also remove edge splits where they are supposed to be. If areas start looking a bit off, it's possible you've removed edge splits that were supposed to be there.

I'm not sure if this has been fixed with the newer GMDC import, but for OBJ meshes you need to do it this way.

Ow that sucks Yeah, I know how to fix it manually, but on more complicated meshes it's too troublesome to restore the correct splitting. Anyway, thanks for replying!

What is this GMDC import you're talking about?

It's for clothes and other animated meshes. I think this is the newest:
https://modthesims.info/d/656032/th...ender-2-80.html

One for older versions here:
https://modthesims.info/d/612164/up...ender-2-79.html

(I've got no experience with it - there's some instruction in the download topics, and probably also in tutorials using these importers).

It worked! It has a bit of a problem that there's no smoothing between separate meshes, but otherwise it removes doubles correctly, thanks again!

Adding pics just for the record. pic1 - all mesh parts, pic2 - one of the parts hidden, in the original mesh that place is all smoothed as one.

If you've imported a food item like a cake (especially from TS4), some of the items are likely layered, so you may not need everything, or you'll need to build it up in a different way. Depends on whether you're making a deco item or a food item in TS2.